1. Field of the Invention
The present invention relates to a structure for high voltage bearable transformers, and particularly to a structure for high voltage bearable transformers used to drive the backlight driving circuits of the liquid crystal display devices.
2. Description of Related Art
As liquid crystal display devices like LCD monitors and LCD TVs are increasing in size, liquid crystal display devices need more cold-cathode fluorescent lamps to make the light radiated from the liquid crystal display devices brighter and more uniform.
FIG. 1 shows a conventional structure for a transformer 1, which has two symmetrical main bobbins 11 adjacent to each other. The bobbins include a primary bobbin 12 and a secondary bobbin 13 respectively. There are pins 14 set at the ends of the main bobbins 11. There are several winding troughs 131 and partitions 132 set on the secondary bobbins. Each partition 132 has two winding-cross ditches 133 at two ends of each partition 132. Users may wind the primary windings (not shown in FIG. 1) on the primary bobbins 12 and wind the secondary windings (not shown in FIG. 1) on the secondary bobbins 13. After supplying power, a driving circuit (not shown in FIG. 1) can drive a cold-cathode fluorescent lamp (not shown in FIG. 1) to light as the primary windings connect to the driving circuit and the pins 14 connect to the cold-cathode fluorescent lamp.
Please refer to FIG. 2 that shows the driving manner for conventional transformers. Because there is only one set of primary windings 111, a pair of pins 112, one set of secondary windings 134, and another pair of pins 135 on the magnetic circuit 15, conventional transformers are only able to connect with one driving unit. Because a full-bridge driving unit, a half-bridge driving unit or a push-pull driving unit has been chosen, conventional transformers can't use pair wire coil for lowering the temperature. Subsequently, only a high voltage output may be exported. Moreover, as shown in FIG. 3, this may cause the peak value of the voltage to rise at the high voltage end of conventional transformers causing burn out in the transformers where the secondary windings 134 are coiled on one winding trough 131 of the secondary bobbins 13 and then cross the winding-cross ditches 133 directly and proceed to be wound on the next winding trough 131.
Because conventional transformers can only export a high voltage output to drive a cold-cathode fluorescent lamp, cold-cathode fluorescent lamps must connect to an equal amount of transformers that increases the volume of the liquid crystal display devices and cause transformers to burn out due to a voltage over load. Because conventional transformers have the above mentioned problems, a structure for high voltage bearable transformers that improves upon these problems is desired.